Improv Everywhere, the pranksters behind such internet classics as the Grand Central freeze and the No Pants Subway Ride, recently did a tour of four North American cities to hold their MP3 experiments. These consisted of thousands of people getting together, each with a special MP3 loaded up on their portable audio players, and then following the instructions en masse. What resulted was a bunch of completely insane battles between huge groups of people wielding balloons, all listening to headphones. Only in the age of the internet could huge groups of strangers get together to participate in such well-organized lunacy. Be sure to sign up for IE's mailing list if you want to get on board for the next one. [Improv Everywhere]